The present invention relates to an inlet and outlet, preferably a funnel inlet and funnel outlet, at the ends of a measurement pipe provided with ultrasonic transducers, with a measurement channel for gas flow measurement, in which the inlet and outlet effect a deflection of the gas flowing into and out of the measurement channel, respectively.
In addition to the long-established bellows gas meters, ultrasonic gas flowmeters are also used for gas flow measurement. In the case of the use of ultrasonic gas flowmeters as gas meters, a problem arises that the connection to pipe connections pointing parallel upwards must be undertaken in accordance with a so-called U6 arrangement as a standard configuration. Furthermore, the space available for the installation of an ultrasonic gas flowmeter is limited, so that only measurement pipes of limited length can be used for the ultrasonic gas flow measurement. However, this restriction has an influence on the accuracy of measurement and is even further intensified if the length of the measurement pipe is additionally shortened on account of laterally fitted pipe connections for the inlet and outlet of the gas. Moreover, such a solution results in a distorted characteristic.
An inlet and outlet of the above-mentioned type is disclosed in Patent Document No. GB 2 205 645. In this type of inlet and outlet, the rate of flow of a liquid is measured, which liquid is conducted through a measurement pipe designed in a U-shape. The ends of the measurement pipe serve as an inlet and outlet and are angled off by 90.degree. in relation to the region which functions as a measurement path. The cross section of the measurement pipe is equally large at all positions.
European Patent Application Number 0 347 096 reveals a measurement channel with ultrasonic transducers and a funnel-shaped inlet and outlet which are both disposed coaxially in relation to the measurement pipe. However, the two funnels do not effect any deflection of the gas flowing through the funnels.